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Regulating Eukaryotic Gene Expression
Fig 15.1
Why change gene
expression?
•Different cells need
different components
•Responding to the
environment
•Replacement of
damaged/worn-out parts
Two points to keep in
mind:
1. Cellular components
are constantly turnedover.
2. Gene expression takes
time:
Typically more than an
hour from DNA to
protein. Most rapidly
15 minutes.
Fig 15.1
•Gene expression can be
controlled at many
points between DNA and
making the final
proteins.
•Changes in the various
steps of gene expression
control when and how
much of a product are
produced.
Fig 15.1
Gene Expression is controlled
at all of these steps:
•DNA packaging
•Transcription
•RNA processing and
transport
•RNA degradation
•Translation
•Post-translational
Fig 15.1
Fig 16.1
Gene Expression is controlled
at all of these steps:
•DNA packaging
•Transcription
•RNA processing and
transport
•RNA degradation
•Translation
•Post-translational
Fig 15.1
Fig 16.1
Tightly packaged DNA is unavailable. DNA
packaging changes as the need for different
genes changes.
Fig 10.21
Different levels of DNA packaging
Fig 10.21
Histones can be posttranslationally
modified, which
affects their abililty
to bind DNA.
Fig 12.15
Acetylation (-COCH3):
post-translational
modifications of the
histones loosen DNA
binding
Acetylation of histones
(-COCH3) causes a
loosening of the
DNA/histone
bond…unpackaging the
DNA.
Fig 15.13
DNA methylation
DNA methylation often inhibits transcription
Fig 15.14
Epigenetics:
the inheritance of
DNA modifications,
including
methylaton
Fig 15.15
Gene Expression is controlled
at all of these steps:
•DNA packaging
•Transcription
•RNA processing and
transport
•RNA degradation
•Translation
•Post-translational
Fig 15.1
Fig 16.1
Eukaryotic transcription must be activated by
binding of transcription factors
Fig 12.14
Mutations in the promoter show critical
nucleotides
Fig 15.12
Enhancers are regulatory regions located
some distance away from the promoter
Proteins that help bend DNA can play an
important role in transcription
Fig
15.12
Fig 15.12
DNA bends to bring different areas in to close
contact.
How do eukaryotic cells jointly express
several proteins (without operons)?
Promoter sequences where transcription
factors can bind activating multiple gene in
response to the environment
Fig 12.13
Promoters typically have several regulatory
sequences
Steroid response element
Fig 15.6
•Steroids bind to
receptors/transcription
factors inside cell
•get translocated to the
nucleus
•bind to promoters and
activate transcription.
cytoplasm
Gene Expression is controlled
at all of these steps:
•DNA packaging
•Transcription
•RNA processing and
transport
•RNA degradation
•Translation
•Post-translational
Fig 15.1
Fig 16.1